diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/liveupdate/kexec_handover.c | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c index bc7f046a1313..5c5c9c46fe92 100644 --- a/kernel/liveupdate/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -4,6 +4,7 @@ * Copyright (C) 2023 Alexander Graf <graf@amazon.com> * Copyright (C) 2025 Microsoft Corporation, Mike Rapoport <rppt@kernel.org> * Copyright (C) 2025 Google LLC, Changyuan Lyu <changyuanl@google.com> + * Copyright (C) 2025 Pasha Tatashin <pasha.tatashin@soleen.com> */ #define pr_fmt(fmt) "KHO: " fmt @@ -1117,6 +1118,92 @@ err_free_pages_array: } EXPORT_SYMBOL_GPL(kho_restore_vmalloc); +/** + * kho_alloc_preserve - Allocate, zero, and preserve memory. + * @size: The number of bytes to allocate. + * + * Allocates a physically contiguous block of zeroed pages that is large + * enough to hold @size bytes. The allocated memory is then registered with + * KHO for preservation across a kexec. + * + * Note: The actual allocated size will be rounded up to the nearest + * power-of-two page boundary. + * + * @return A virtual pointer to the allocated and preserved memory on success, + * or an ERR_PTR() encoded error on failure. + */ +void *kho_alloc_preserve(size_t size) +{ + struct folio *folio; + int order, ret; + + if (!size) + return ERR_PTR(-EINVAL); + + order = get_order(size); + if (order > MAX_PAGE_ORDER) + return ERR_PTR(-E2BIG); + + folio = folio_alloc(GFP_KERNEL | __GFP_ZERO, order); + if (!folio) + return ERR_PTR(-ENOMEM); + + ret = kho_preserve_folio(folio); + if (ret) { + folio_put(folio); + return ERR_PTR(ret); + } + + return folio_address(folio); +} +EXPORT_SYMBOL_GPL(kho_alloc_preserve); + +/** + * kho_unpreserve_free - Unpreserve and free memory. + * @mem: Pointer to the memory allocated by kho_alloc_preserve(). + * + * Unregisters the memory from KHO preservation and frees the underlying + * pages back to the system. This function should be called to clean up + * memory allocated with kho_alloc_preserve(). + */ +void kho_unpreserve_free(void *mem) +{ + struct folio *folio; + + if (!mem) + return; + + folio = virt_to_folio(mem); + WARN_ON_ONCE(kho_unpreserve_folio(folio)); + folio_put(folio); +} +EXPORT_SYMBOL_GPL(kho_unpreserve_free); + +/** + * kho_restore_free - Restore and free memory after kexec. + * @mem: Pointer to the memory (in the new kernel's address space) + * that was allocated by the old kernel. + * + * This function is intended to be called in the new kernel (post-kexec) + * to take ownership of and free a memory region that was preserved by the + * old kernel using kho_alloc_preserve(). + * + * It first restores the pages from KHO (using their physical address) + * and then frees the pages back to the new kernel's page allocator. + */ +void kho_restore_free(void *mem) +{ + struct folio *folio; + + if (!mem) + return; + + folio = kho_restore_folio(__pa(mem)); + if (!WARN_ON(!folio)) + folio_put(folio); +} +EXPORT_SYMBOL_GPL(kho_restore_free); + static void __kho_abort(void) { if (kho_out.preserved_mem_map) { |